This invention relates to electric motor construction, and more particularly to subfractional horsepower alternating current motors. Many such small motors are constructed with two bearings in the frame or stator for journaling the rotor shaft near each end thereof.
The present invention is primarily concerned with a single or unit bearing motor wherein there is only one fixed bearing which journals a single journal portion on the rotor shaft. Motors of this type are shown in U.S. Pat. Nos. 2,053,425; 4,209,722; and 4,499,661. Different methods have been suggested in these patents for driving a load from the rotor. The torque is developed in the rotor conductors, transferred to the rotor mass, from there to the shaft, and then to the load. One typical example is to grind or mill a flat on the steel shaft so that the shaft will have a non-circular configuration, and hence transmit torque to a load connected to the shaft at the area having the flat. This is shown in U.S. Pat. No. 2,053,425.
Another means to transmit torque to a load is by utilizing a threaded end on the shaft to receive a nut for securing the load onto the rotor shaft. All of these prior methods require extra machining on the shaft in order to obtain a non-circular cross section for transfer of torque to the load. Usually, the load has to have a cross section of hub aperture the same diameter as the motor shaft.